Med Micro Lab Practical

Front 1

a medium that contains living microbes

Back 1

culture

Front 2

a culture that contains a single species

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pure culture

Front 3

without contamination of yourself, others, the environment, the source culture, or the medium being inoculated

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aseptic

Front 4

what are the seven general techniques that improve your chances of making an aseptic transfer?

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1.) minimize the potential of contamination

2.) be organized

3.) place all media tubes in a test tube rack when not in use whether they are sterile or not

4.) take your time

5.) never hold a tube culture by it's cap

6.) hold the inoculating loop or needle like a pencil in your dominant hand and relax

7.) adjust your bunsen burner so its flame has an inner and outer cone

Front 5

where should you write on your petri plates?

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the base

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used to grow microbes when fresh cultures or large numbers of cells are required

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broths

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generally used to grow stock cultures that can be refrigerated after incubation and maintained for several weeks

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agar slants

Front 8

typically used for obtaining isolation of species, differential testing, and quantifying bacterial densities

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plated media

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instruments usually used for transfers

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inoculating loops or needles

Front 10

what is the concern with BSL-2 organisms?

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aerosol production

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what do you label with?

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your name, the date, the medium, and the organism's name

Front 12

what are two important things to remember about aseptic technique? (according to class)

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1.) exclusion

2.) heat

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group of microorganisms that are visible to the naked eye

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colony

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what are the 6 aspects of colony morphology?

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1.) color

2.) shape

3.) size

4.) texture

5.) elevation

6.) margin-edge of colony

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a microbial culture consisting of two or more species

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mixed culture

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the colony origin

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colony-forming unit (CFU)

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way to separate bacteria

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streak plate

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functions of a streak plate?

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1.) separate bacteria to form isolated colonies (pure culture)

2.) check purity (colony morphology)

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do not reside on or in a specific plant or animal

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free-living

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not known to cause disease

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nonpathogenic

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perform the important ecosystem role of decomposing organic matter

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saprophytes

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if they cause damage to the host and cause disease what are they called?

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pathogens

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microbe benefits their host

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mutualism

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microbe benefits but has no significant effect on their host

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commensals

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capable of producing a disease state if introduced into a suitable part of the body (seen in commensal or mutualistic strains)

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opportunistic pathogens

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any area including sites outside of the host organism where a microbe resides and serves as a potential source of infection

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reservoir

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example of a biogeochemical cycle

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the sulfur or nitrogen cycles

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different shapes of colony morphologies

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round (circular), irregular, or punctiform (tiny, pinpoint)

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different margins (edges) of colony morphology

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entire (smooth, with no irregularities), undulate (wavy), lobate (lobed), filamentous (unbranched strands), or rhizoid (branched like roots)

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different surface types of colony morphology

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smooth, rough, wrinkled, shiny, or dull

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texture of colony morphology

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moist, mucoid (sticky), buttery, or dry

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elevations of colony morphology

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flat, raised, convex, pulvinate (very convex), and umbonate (raised in the center)

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concentrates the light and makes illumination of the specimen more uniform

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condenser lens

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bending of light

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refraction

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produces a magnified real image

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objective lens

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produces a virtual image that appears below or within the microscope

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ocular lens

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total magnification formula

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total mag. = mag. by the obj. lens X mag. by the ocular lens

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clarity of an image

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resolution

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an actual measurement of how far apart two points must be for the microscope to view them as being separate

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limit of resolution (or resolving power)

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the measure of a lens's ability to "capture" light coming from the specimens and use it to make the image

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numerical aperture

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a special condenser is used so only the light reflected off the specimen enters the objective

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dark-field microscopy

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uses special optical components to exploit subtle differences in refractive indices of water and cytoplasmic components to produce contrast

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phase contrast microscopy

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uses a fluorescent dye that emits fluorescence when illuminated with UV radiation

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fluorescence microscopy

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a colored molecule in a stain; often a benzene derivative

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chromogen

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the portion of the chromogen that gives it it's color

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the chromophore

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the charged portion of a chromogen and allows it to act as a dye through iconic or covalent bonds between the chromogen and the cell

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auxochrome

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attracted to the negative charges on the surface of most bacterial cells

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basic stains

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what are some common basic stains?

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methylene blue, crystal violet, and safranin

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kills bacteria, makes them adhere to the slight, and coagulates cytoplasmic proteins to make them more visible

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heat fixing

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bottom of a slide

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smooth side

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stain the cell; basic stains; take on a positive charge (crystal violet, methylene blue, safranin)

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positive simple stain

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stain the background; acidic stains (migrosin, congored)

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negative stain

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simple stains are useful for determining what?

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cell shape and arrangement

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bacterial cells typically have a _____ charge

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negative

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positive charged stains attract a ______ cell

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negative; so cell gets stained

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consists of a decolorization step between the application of two basic stains

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the gram stain

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primary stain

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crystal violet

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iodine is added as a ______ to enhance crystal violet staining

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mordant

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what comes next?

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decolorization

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______________ cells are decolorized by the solution

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gram-negative cells

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___________ can be colored by the red counterstain

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gram-negative cells

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counterstain

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safranin

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gram positive cells appear __________

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purple

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gram negative cells appear ___________

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reddish-pink

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leaving the decolorized on too long and get reddish gram-positive cells

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over-decolorize

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produce purple gram negative cells

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under decolorize

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allows you to tell diff. between 1 group of M/O and other group

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differential stain

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what are the functions of a gram stain?

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1.) gram reaction - gram pos. or neg.

2.) shape and arrangement

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what turned purple in lab?

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bacillus subtilis and staphylococcus aureus

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what turned pink in lab?

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escherichia coli

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what are the steps of a gram stain?

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1.) stain smear with crystal violet (60 sec) and rinse

2.) stain with gram's iodine (60 sec) and rinse again

3.) decolorize smear using 95% ethanol and risk immediately (for 10 seconds or once drops are colorless)

4.) stain with safranin (60 sec) and rinse

Front 72

why do gram positives have a lot of crystal violet and don't decolorize?

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thicker cell wall

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can only do a gram stain if bacteria is ________ hours old

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18-20